Implantable ophthalmic sensor cell

ABSTRACT

An implantable ophthalmic device connectable to an implantable accommodating lens includes a dual-chamber sensor cell having a first and second plate where the second plate is disposed opposite the first plate. A first chamber with a first flexible membrane is disposed on an inner side of the first plate. A second chamber with a second flexible membrane is disposed on an inner side of the second plate. A space resides between the first and second chambers configured to receive a scleral spur of a ciliary muscle of a patient&#39;s eye. A connecting element is attached at a first end to the dual-chamber sensor cell. The connecting element includes a first and second channel disposed along a length of the connecting element and in communication with the first and second chamber of the dual-chamber sensor cell, respectively. The second end of the connecting element is connectable to the implantable accommodating lens.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of application Ser. No. 13/247,840filed Sep. 28, 2011, which claims priority from provisional applicationSer. No. 61/514,413 filed Aug. 2, 2011, the entire contents of which arehereby incorporated by reference.

FIELD OF THE INVENTION

The present invention relates generally to a diffractive lens thatcreates an image at different positions sequentially by the change inmagnitude of the surface relief structure height at its diffractivesurface, and more particularly to a diffractive ophthalmic lens thatchanges surface relief structure height at one of its surfaces toprovide distance and near foci, and even more particularly todiffractive accommodating lens that changes surface relief structureheight under the action of ciliary muscle.

BACKGROUND OF THE INVENTION

The diffractive lens of this disclosure can be applied outside or withinophthalmic application. In later case the lens is called ophthalmiclens. Ophthalmic lens in this disclosure is defined as a lens suitablefor placement outside the eye such as spectacles or contact lenses orinside the eye such as aphakic and phakic intraocular lenses placed inposterior or anterior eye chamber and also included are less commonvision correction lenses such as artificial corneas and cornealimplants.

For detailed explanation of the lens of this invention, the applicationin the ophthalmology for Presbyopia correction and more particularly toaccommodating optic is used as a preferred embodiment.

A fixed single power lens provides good quality vision but only within asmall range of viewing distances that is usually significantly narrowerthan the range required from near to distant vision. The resulted visiondeficiency is called Presbyopia. There is a significant effort todevelop a lens for Presbyopia correction in a form of multifocalrefractive or diffractive type lenses that provide multiple foci andalso in a form of accommodating lenses that may change their externalsurface shapes or positions inside the eye for incremental powerincrease for near vision. Accommodating ophthalmic lens described inthis disclosure is a lens that consequently changes the image positionsbetween distance and near foci by directing most of the available lightto different diffractive orders or between refractive state and one ofthe diffractive orders under the action of ciliary muscle. It isimportant to note that lens disclosed in this invention has applicationoutside accommodation and outside ophthalmic.

Natural accommodation as vision phenomenon is the ability of the eye tofocus at different distances. It involves the dioptric power change ofthe eye provided by the crystalline lens shape change. The accommodationis a multistage process and involves a number of ocular elements:ciliary muscle, ciliary body, zonules, and lens capsule and, at last,the crystalline lens itself, FIG. 1. It also involves dynamicallyopposite actions of the corresponding ocular elements such as ciliarymuscle vs. zonules/capsular bag. For instance, to accommodate for nearvision, the ciliary muscle contracts which moves the ciliary body inwardtowards the crystalline lens, this relaxes the zonules attached to theciliary body which in turn, releases the elastic capsular bag to allowthe crystalline lens inside the capsular bag to take a more roundedshape for higher optical power. For far vision, the ciliary musclerelaxes which moves the ciliary body outward from the crystalline lens;this creates tension on zonules which in turns stretches the capsularbag that flattens the crystalline lens inside the crystalline bag toreduce the optical power of the lens.

All the involved in accommodation ocular elements and especially zonulesand capsular bag vary with age and between different individuals thusmaking an accommodating device that relies on the action of zonules andcrystalline bag to work as an extremely challenging task.

It has been several efforts to develop ophthalmic lens that can switchbetween optical conditions for far and near vision since 80th by usingrefractive optic. The principle of adjustment can be divided into threetypes of approached: (1) deformable design that changes lens shape inorder to change its power, (2) translatable design that changes lensposition inside the eye in order to change eye power and (3) refractiveindex adjustment design that changes lens material refractive index inorder to change its power. All these designs were disclosed for theapplications to the ocular implants and spectacles; no application tocontact lens has been uncovered.

There are numerous US patents on and descriptions of deformable designs(Fluid Vision, Flex Optic, NuLens, etc.) and translatable designs(Synchrony, Crystalens, HumanOptics, TetraFlex, etc.) for ocularimplants where all of them utilize refractive optics. Deformable designwas also applied to spectacles, for instance variable focus spectaclelens where the surface radius changes were described by Fujita andIdesawa (Fujita T and Idesawa M, “Accommodation Assisted Glasses forPresbyopia”, Proceedings of the SPIE, 2002; 4902:99-109). Theinteresting aspect of this paper is the description of the gaze trackingfor automatic lens power adjustment for viewing object distance.

There are also few US patents on refractive index modification designs.Nishimoto in U.S. Pat. No. 4,564,267 suggested a variable focal lensusing the Pockels effect by applying electric filed to the electro-opticcrystal to change material refractive index. Similar idea was disclosedby Kern in the U.S. Pat. No. 4,601,545 using liquid crystal. Kern alsoproposed the application of his invention to intra-ocular and spectaclelenses (Kern S P, “Bifocal, electrically switched intraocular andeyeglass molecular lenses” Proceedings of the SPIE, 1986; 601:155-158).

All the above disclosure was based on refractive optic for accommodationapplication. Diffractive lens application to accommodating implant wasdisclosed by Portney in US Patent Application No: 20070032866 where themonofocal diffractive optical surface changes its periods by bending inresponse to the accommodating force from the ocular element of the eyethus changing a separation between the diffractive orders and shiftingthe diffraction image focus from one position to another. Publication20070032866 did not disclose a change in surface relief height to switchlight from one diffractive order to another to take full advantage ofdiffractive optic to maintain constant Add power as the separationbetween the diffraction orders and still relied on continuous change infocus position similar to a refractive optic.

Diffractive optic offers advantages over refractive optic for Presbyopiatreatment where switching between far and near vision is requiredinstead of continuous change of optical power of refractive optic whereeach power position is much more difficult to control and where farvision, for instance, may be easily varying even with a small change ofaccommodating force. More detailed explanation of diffractive opticadvantages is provided below.

The advantage of the diffractive optic in switching between far and nearover the refractive optic was described in the application to thespectacle lens by a large group of researches: Li G, Mathine D L, ValleyP, et al. “Switchable electro-optic diffractive lens with highefficiency for ophthalmic application”, Proceedings of the NationalAcademy of Science of the USA, 2006; 103: 6100-6104. The operation ofthe described spectacle lenses was based on electrical control of therefractive index of thin layer of pneumatic liquid crystal. Though theapproach is feasible, it is very complicated and expensive to executeand it also requires elective field control for its operation which isproblematic for ocular implants and contact lenses. Haddock at el. in USPatent Application 20090256977 introduced further improvements to theabove diffractive lens manufacturability. The spectacle lenses under theabove design were released by PixelOptics under EmPower trade name.

The described above systems used the electro-optical switching betweendiffractive states for far and near vision by refractive indexmodulation. The present invention utilizes mechanical optical switchingbetween far and near vision by changing the height of the surface reliefstructure of the diffractive optic.

The present disclosure also describes the diffractive optic withprogressively changing foci by adjusting the periods of the diffractivegrooves. This can be applied not only to the surface relief periodicstructure of static single focus and multifocal diffractive lens wherethe light split is constant and also to dynamic diffractive lens wherelight is redirected between different diffractive orders by mechanicalor electro-optical means of refractive index or surface reliefmodulations.

Iyer et al. in the US Patent Application 20110176103 referenced torefractive-diffractive insert that provided progressive power variationby optical communication between refractive and diffractive regions. Noreference to a diffractive optic that on its own provides progressivefoci by adjusting the periods of the diffractive grooves was disclosurein lyer's US Application.

Diffraction principle of image formation is utilized for the disclosedaccommodating ophthalmic lens. A diffractive lens consists of a periodicstructure responsible for the separation between produced diffractiveorders and is characterized by its phase function analogous to arefractive lens description by its surface sag equation. There two waysto change phase delay in the diffractive structure of a diffractiveoptical element and switch or redirect light between different foci,either by refractive index modulation or by surface shape (relief)modulation. Therefore, there are two types of diffractive structures:(1) refractive index modulation structure and (2) surface reliefstructure. First approach has been applied to spectacles as referencedabove publication by Li and his colleagues. For the purpose ofreferencing in this disclosure, the first approach to switch or redirectlight between different foci by refractive index modulation is calleddiffractive accommodating lens by refractive index modulation and thesecond approach to switch or redirect light between different foci bysurface relief modulation is called diffractive accommodating by surfacerelief modulation.

The proposed invention is based on the modulation of the surface reliefstructure by maintaining its period and, therefore, separation betweendiffractive order and changing its height in order to control lightdistribution between the diffractive orders. In the other diffractivestructure that relies on the refractive index modulation, the maximumthickness of the material within which the refractive index changes isanalogous to the higher of the surface relief structure as explainedabove. For the purpose to simplify a description of the refractivemodulation structure, the maximum thickness of the material within whichthe refractive index changes is defined as the “refractive indexamplitude” in this embodiment.

The disclosed invention is applicable not only to spectacles lens butcontact lenses and ocular implants. Thus, the surface relief structureof this invention maintains the same period but otherwise changes itsheight in order to provide accommodation between far and near vision.

A surface relief structure of diffractive surface can be formed bydifferent types of zone or groove shapes (sine, rectangular, forinstance) and a blaze shape shown on the FIG. 2 being the most commonone. A specific periodic blaze shape is cut into a refractive surfacewhich becomes the base surface of the diffractive surface and theresulted lens becomes a diffractive lens.

This disclosure will use blaze grating as an example but the presentinvention is applied to any type of surface relief diffractive surfacethat produces distance and near foci or, more generally, at least twoimages at its diffractive orders by shifting 100% or substantial portion(about 30% or more) of light to different diffraction orders orrefractive image position and a position defined by one of thediffraction orders.

The distances from the diffractive surface to the foci created by thediffraction orders can be quantified in terms of diffraction powersassociated with the diffraction orders similarly to a refractive lenspower definition. Zero-order diffractive power of the diffractivesurface coincides with the refractive power of the refractive surfacesformed by the base surface of the diffractive surface.

By the law of formation of a diffraction order, light can only bechanneled along the diffraction orders of the diffractive lens whereconstructive interference can take place. It leads to the discrete fociof a diffractive lens. Discrete nature of image formation by adiffractive optic is the key characteristic utilized by the diffractiveaccommodating lens of this invention.

Importantly, the image is physically formed at a given foci of thediffraction order if a measurable percent of total light is actuallychanneled along a given diffraction order. This depends upon the lightphase shift introduced by each blaze zone, i.e. groove height or blazematerial thickness (h), FIG. 2. The construction of accommodating cellof the diffractive accommodating lens of this invention is to controlthe change of the blaze material thickness in order to channel 100% oflight or most of the available light consequently between twodiffractive orders or a diffractive order and refractive state where thegrooves height is zero. These two image positions associate with far andnear foci.

Geometry of the diffraction grooves is easier to explain by the“geometrical model” of the grating: 100% efficiency (lighttransmittance) in m-order can be achieved if the direction of theimaginable blaze ray defined by the refraction at the blaze coincideswith the direction of m-order diffraction, (Carmifia Londofio and PeterP. Clack, Modeling diffraction efficiency effects when designing hybriddiffractive lens systems, Appl. Opt. 31, 2248-2252 (1992)). It simplymeans that the blaze material thickness is designed to direct the blazeray along the m-order diffraction produced by the blaze groove widthsfor the design wavelength of light.

In a simple paraxial form the circular grating zones, also calledgrooves, echelettes or surface-relieve profile, can be expressed by theformula r_(j) ²=jmλf, i.e. the focal length of m-order diffraction(m=±1, ±2, etc.) for the design wavelength (λ) can be closelyapproximated by the following formula:

$\begin{matrix}{f_{m} = \frac{r_{j}^{2}}{{jm}\; \lambda}} & (1)\end{matrix}$

This is the formula typically used for the groove widths calculation indiffractive optic that produces wavefront close to a spherical shape,i.e. small amount of aberration. The locations of groove's borders aresimply determined analytically by radii radii r_(j). The radii perEquation 1 define diffractive lens periodic structure which, in thiscase, produces spherical wavefront that defines single focal length(f_(m)) for diffractive order (m). In general, the periodic structurecan be surface relief structure where surface shape manifests theperiodic structure per Equation 1 or close to it to producequasi-spherical wavefront, or refractive index modulation structurewhere the material variation of the diffractive lens manifestsrefractive index periodic structure per Equation 1.

In case of the surface relief structure, and in the paraxialapproximation the blaze material thickness to produce 100% efficiency atm-order is

$\begin{matrix}{h_{m} = \frac{m\; \lambda}{\left( {n - n^{\prime}} \right)}} & (2)\end{matrix}$

where n=refractive index of the lens material and where m=refractiveindex of the surrounding medium.

A surface relief may be formed by different shapes of the periodicdiffractive structure and not only by a blaze shape and for thegenerality of the present invention the term “groove” is used as thedescription of the variety of shapes of the diffractive structureincluding multi-order phase grating (MOD) which is useful in reducingdispersion or chromatic aberration of the diffractive optical element.

Phase function defines diffractive optic analogous to sag equationdefining refractive optic. A phase function is usually defines inpolynomial form as shown by the equation 3 below, The examples of thephase functions in terms of polynomial phase coefficients is provided inthe Table 3 for diffractive optic with small and large sphericalaberrations.

In case of small aberration, the periodic structure of the diffractiveoptic is quite accurately defined by the equation 1 for given focaldistance. In case of significant spherical aberration of the diffractivelens to be introduced in order to extend the range of vision around oneof the focus of the diffractive order, the calculation of the grooveshapes can be conducted numerically similar to the method described byPortney in the US Patent Appl. No: 20100066973 for multifocaldiffractive lens:

a) calculating diffractive structure phase coefficients that producediffractive focus of a selected accommodating state. Usually (−1)-orderdiffraction is allocated to near focus.

$\begin{matrix}{{\Phi_{- 1}(r)} = {\frac{2\pi}{\lambda}\left\lbrack {{a_{1}r} + {a_{2}r^{2}} + \ldots + {a_{n}r^{n}}} \right\rbrack}} & (3)\end{matrix}$

Formula (3) is (−1)-order (near focus) phase function with phasecoefficients α_(i) calculated over the contribution of the eye opticalsystem.

b) numerically calculating a 100% diffraction efficiency groove shapeand height h(r_(i)) that produces the defined phase coefficients and thegroove widths defining by the phase function modulo 2πp cycle where p=1,2, . . . .

The objective of the present invention is to provide a diffractiveaccommodating lens that offers a sequential change in the optical stateswith substantial portion of the available light switched or redirectedbetween two images for far or near vision under the action of theciliary muscle contraction and relaxation. The lens that forms images attwo image positions with image at one image position is formed bynon-zero order diffraction and image at another image position isfainted by either a different order diffraction or refraction isdisclosed by this invention.

The invention offers also an option to bypass the ocular elements suchas zonules and capsular bag which reduce a reliability of anaccommodating lens and rely on the direct interaction with the ciliarymuscle. This is accomplished due to the ability to the diffractiveaccommodating lens of this invention to switch foci between far and nearvision by only a small amount of the material transfer which can beaccomplished by the ciliary muscle action. A volume of the materialtransfer involved in the diffractive accommodating lens of thisinvention is only in a small fraction of milliliter.

A material transfer in accommodating optic may occur directly from asensor cell implanted or installed next to ciliary muscle in order torespond to their relaxation and contraction. This is accomplished inocular implants such as aphakic, phakic including corneal implants. Amaterial transfer may occur indirectly from a sensor cell by the celltransferring electronic signal to an external visual aid suchspectacles, for instance, to control its optical states between far andvision. Ultimately, electronic transfer signal can be conducted betweensensor cell and implants with optical state change per these inventionsby mechanical or electronic means.

As a minimum, the lens of the present invention may still rely on theinteraction with the capsular bag or vitreous as indirect means torespond to ciliary muscle actions during accommodation.

The invention disclosures different option for optical enhancement ofthe range of vision at image formed at the diffraction order on theexample of extending the range towards intermediate vision from the nearvision formed by (−1)-order diffraction.

In the present invention the periodic structure of the diffractivesurface is maintained between the optical states of far and near visionbut the phase delay changes between when switching between these opticalstates. The invention disclosure describes surface relief diffractivelens that switches optical states of far and near vision by changingphase delay with surface relief height.

Certain invention disclosures related to multi-zonal use of thediffractive surface the zones have different periodic structure toprovide different foci for the same diffractive order is applicable togeneral phase delay wither by the height of the surface relief orrefractive index modulation.

Additional invention disclosure describes periodic structure change toincrease spherical aberration and associated with it depth of focusaround focus position produced by non-zero diffractive order as comparedwith diffractive lens with small amount of spherical aberration. Thisdisclosure is applicable to static diffractive multifocal lens wherelight split is constant as well as to dynamic diffractive accommodatinglens where light split between far and near vision changes.

The invented lens can be applied outside the eye in a form ofspectacles, contact lens or even in non-ophthalmic applications requiredthe image position change without moving the lens itself.

SUMMARY OF THE INVENTION

A lens in accordance with the present invention consists of front andback surfaces and accommodating cell situated between them. In aparticular embodiment, the accommodating cell consists of two chamberswith at least one chamber filled with optical fluid with the refractiveindex matching the refractive index of the accommodating elementseparating the chambers. The accommodating element is having the surfacerelief structure that maintains its period but changes its height duethe pressure difference between the chambers. The accommodating cell mayinclude another chamber connected with the external to the lens medium(aqueous humour, air, stroma, tear layer). The accommodating cell mayalso have chambers both filled with optical fluids of differentrefractive indices. The accommodating element shape change createsdifferent diffractive groove heights to redirect most of light thatpasses through the lens image forming zone between different imagepositions of far vision and near vision foci. The add power for nearvision is defined by the periodicity of the surface relief structure.Thus, the accommodating element includes formable surface with aplurality of sub-elements disposed on it for temporarily establishing asurface zone with a non-zero relief structure height upon change ofpressure on this formable surface. For instance, one focus can berefractive formed by the refractive surface with surface relief surfacewith zero heights and another focus is formed by the diffractive surfacerelief of specific non-zero height to direct most the available lightthat passes through the lens image forming zone along the correspondingto this height non-zero order diffraction. Another option is to have theone surface relief non-zero height to pass most of light along thecorresponding to this height non-zero order diffraction and then tochange the s height magnitude to direct most of the available lightpassing through the lens image forming zone to another corresponding tothis height non-zero order diffraction.

This invention describes the device called diffractive accommodatinglens or DAL which can overcome the complexity and individual dependenceof the forces involved in eye accommodation. The disclosure involves twoaspects of the invention:

(1) The diffractive accommodating system that includes Sensor Cell andDAL interacts directly with the ciliary muscle in changing its focusstate. It is well known that the ciliary muscle operation is maintainedfor different age thus proving a reliable action for the accommodatingdevice. All other ocular elements involved in the accommodation such aszolules, capsular bag and the crystalline lens itself are highly age andindividual condition dependent and can't be relied on for consistentoperation of accommodating devices. The invention discloses Sensor Cellthat is placed at the location of the Scleral Spur to interact directlywith ciliary muscle and transfer the pressure change to the DiffractiveAccommodating Lens to change its states between far and near vision. Adiffractive accommodating lens DAL according to this invention may alsorely on the secondary accommodating effect where ciliary musclecontraction effects the choroid tension that increases vitreous pressurethat causes crystalline lens-zonule complex to move forward. In thiscase, the crystalline lens is replaced by the DAL and the vitreouspressure change switches the states of the DAL between far and nearvision.

(2) The diffractive accommodating lens DAL provides two states ofaccommodation for far and near vision thus maintaining each state onlytemporary. Technically it means that the device acts in digital binarysense and does not change its accommodation effect if a force exerted byciliary muscle does not exceed certain threshold level. This allowsmaintaining stability of the vision in relaxed state even under somefluctuation of the forces. Thus, the operation of DAL relies only on asingle parameter such as a force threshold between relaxed andcontracted states of the ciliary muscle of a given individual which canbe even adjusted in vivo.

A diffractive lens that directs 100% or most of the available light thatpasses through its image forming zone to (−1)-order diffraction iscalled kinoform and the corresponding diffractive lens acts as one ofthe states of the diffractive accommodating lens DAL of this disclosure,specifically for near focus. A diffractive lens that directs 100% ofmost of the available light to (+1)-order diffraction may also act asone of the states of the diffractive accommodating lens DAL of thisdisclosure, specifically for far focus.

Multifocal diffractive lens is also used to provide two image positionsfor far and near vision for Presbyopia treatment but the issue with thistype of design is that in-focus image at each image position includesout-of-focus image resulted in blur that reduces each image contrast andcontributing to halo and glare perception. One way to quantifymultifocal diffractive lens imaging is to state that total amount oflight used to form in-focus images at certain aperture size is less thantotal amount of the available light entering the lens within the sameaperture size. The reason is that the light is split between in-focusimages at two image positions to form both in-focus imagessimultaneously.

In case of diffractive accommodating lens of this invention, lightutilizes much more efficiently, the total amount of light used to formin-focus images at certain aperture size exceeds the total amount oflight entering the lens within the same aperture size. The reason isthat both in-focus images form sequentially by redirecting some lightfrom in-focus image at one image position to in-focus image at anotherimage position. It is possible that the diffractive accommodating lensof this also invention also split light between the images at two imagepositions simultaneously but the use of light for in-focus image ishigher than in multifocal diffractive lens because the some or allamount of light is redirected inform in-focus image at one imageposition to the in-focus image in another image position. This improvesimage contrast and reduces halo and glare as compared with multifocaldiffractive optic.

The preferred embodiment creates the change between the optical statesof the acting surface by changing pressure between the chambers locatedat both sides from the surface but, in general, the surface shape changefrom one diffractive order to another or to refractive state fordirecting most of the light to one or another image positions can beaccomplished by other means including mechanical transducers orelectrical or magnetic force.

The present disclosure also describes the diffractive optic withprogressively changing foci by adjusting the periods of the diffractivegrooves. This can be applied not only to the surface relief periodicstructure of static single focus and multifocal diffractive lens wherethe light split is constant and also to dynamic diffractive lens wherewith light is redirected between different diffractive orders byelectro-optical or mechanical means by refractive index or surfacerelief modulations. The mechanical means of surface relief modulation toprovide dynamic switch between far and near vision is provided in thisinvention disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The advantages and features of the present invention will be betterunderstood by the following description when considered in conjunctionwith the accompanying drawings, in which:

FIG. 1 illustrates a portion of eye anatomy related to the accommodationprocess. The ciliary body of the eye has three basic functions: aqueousproduction and removal, accommodation, and the formation of vitreousmucopolysaccharide. The ciliary muscle initiates the accommodationprocess and situates inside the ciliary body.

FIG. 2 illustrates a prior art diffractive lens with blazed periodicstructure forming different diffraction orders along which the light canonly be channeled. It illustrates the optical principle used by theaccommodating cell of this invention for switching between far and nearvision. The FIG. 2 also illustrates a “geometrical model” of thediffractive lens through the relationship between the imaginary blazeray defined by the refraction at the blaze and directions of thediffraction orders.

FIG. 3 shows a simplest form of the accommodating cell configuration asa rectangular disc of about 4-6 mm diameter and about 0.1-0.3 mmthickness. The minimum diameter of the accommodating is around 3 mm andmay reach about 6 mm diameter. The thickness can be as small as about0.1 mm. The accommodating cell is situated inside the lens or it maytake the shape of the lens itself by including required surfacecurvatures by its external surfaces instead of flat surfaces shown inthe FIG. 3.

FIG. 4 demonstrates a cross-section of a preferred embodiment of anaccommodating cell in a relaxed state. The accommodating cell of thisembodiment includes two chambers filled with optical fluids, siliconefluid, for instance, separated by the membrane called accommodatingelement that has the ability to change its surface shape with adifference in pressure between the chambers. One chamber is filled withoptical fluid of matching refractive index as the material of theaccommodating element separating the chambers to make the light passingbetween the material separating the chambers and the optical fluidundisturbed by the surface shape facing this chamber. This is opticallytransparent chamber or OTC. Optical fluid of non-matching refractiveindex fills the other chamber. Thus, a light refraction takes place onlyat the surface facing this chamber. This is optically active chamber orOAC. The FIG. 4 demonstrates that the surface facing the chamber filledby optical fluid of non-matching refractive index (OAC) is smoothrefractive surface type for Far vision in relaxed state as one of theexamples of surface configuration.

FIG. 5 demonstrates a cross-section of the accommodating cell, shown inFIG. 4, in a stressed state. The accommodating element between thechambers takes a shape of diffractive surface manifested by thediffractive grooves facing the chamber filled with optical fluid ofnon-matching with the accommodating element material refractive index(OAC). The maximum diffractive grooves heights (blaze materialthickness) is restricted by the geometry of the accommodating elementand the thickness of the chamber filled with optical fluid of matchingrefractive index (OTC), i.e. most of the available light passing theimage forming optical zone of the diffractive accommodating lens isdirected to (−1)-order diffraction by the created diffractive surface ofthe accommodating element.

FIG. 6 demonstrates a cross-section of a preferred embodiment of anaccommodating cell in a relaxed state. The accommodating cell of thisembodiment includes two chambers the first one is filled with opticalfluids, silicone fluid, for instance, and the second chamber isconnected with the external medium surrounding the ophthalmic lens(aqueous humour in case of intraocular lens, stroma or air in case ofcorneal implant, tear layer or air in case of contact lens and air incase of spectacle lens). The chambers are separated by the membranecalled accommodating element that has the ability to change its surfaceshape with a difference in pressure between the chambers. First chamberis filled with optical fluid of matching refractive index as thematerial of the accommodating element separating the chambers to makethe light passing between the material separating the chambers and theoptical fluid undisturbed by the surface shape facing this chamber. Thisis optically transparent chamber or OTC. Thus, a light refraction takesplace only at the surface facing the chamber. The second chamber isoptically active chamber or OAC. The FIG. 6 demonstrates that thesurface facing the second chamber is smooth refractive surface type forFar vision in relaxed state as one of the examples of surfaceconfiguration.

FIG. 7 demonstrates a cross-section of the accommodating cell, shown inFIG. 6, in a stressed state. The accommodating element between thechambers takes a shape of diffractive surface manifested by thediffractive grooves facing the second chamber connected to the externalmedium of the ophthalmic lens. The maximum diffractive grooves heights(blaze material thickness) is restricted by the geometry of theaccommodating element and the thickness of the second connected withexternal medium, i.e. most of the available light passing the imageforming optical zone of the diffractive accommodating lens is directedto (−1)-order diffraction by the created diffractive surface of theaccommodating element.

FIG. 8 demonstrates an assembly of the accommodating cell consisting ofthree elements: front and back membranes to form external walls of thecorresponding chambers filled with optical fluids and accommodatingelement forming the wall between the chambers. The membrane is shown asflat surfaces but can be curved to provide refractive powers. Theconstruction of the accommodating element can be made with diffractivesurface of 1-order diffraction for far vision and refractive surface fornear vision or even as switching between surface reliefs of differentheights to redirect light to the corresponding different ordersdiffraction.

FIG. 9 illustrate front view of one of the embodiments of intraocularlens consisting of lens optic, haptics or supporting elements andaddition of the connecting flexible element attached to theaccommodating element situated inside the intraocular lens of thisembodiment. The connecting element is to connect the accommodatingelement with the sensor cell that interacts with the ciliary muscle totransfer the force from the ciliary muscle contraction and relaxationinto a difference in pressure between the chambers of the accommodatingcell.

FIG. 10 shows the cross-section of the intraocular lens of FIG. 7. Itdemonstrates the accommodating cell situated inside the intraocular lenswith connecting element attached to it at one end and the other endattached to the opposite edge of the intraocular lens optic for itstemporary fixation during the lens implantation inside the eye. This endof the connecting element is separated from the intraocular lens afterthe implantation connection to the sensor cell.

FIG. 11 illustrates the assembly of the intraocular lens shown on theFIGS. 7 and 8. The intraocular lens assembly of this particularembodiment consists of three elements: front element which can beattached to the back element by the front wedge and the accommodatingcell placed between them. Simplest plano-convex shape of the frontelement allows making inexpensive variation of its opticalcharacteristics such as dioptric power, asphericity and toricity forastigmatism correction. Back element of this example incorporates alsohaptics and is of more complex shape and is less variable element of theintraocular lens. Accommodating cell is secured inside the lens to allowthe overall intraocular lens to demonstrate a conventional shape of atypical non-accommodating lens.

FIG. 12 illustrates the connection between sensor cell and accommodatingcell. The connecting element is about 6 mm in length which is adequateto place the sensor cell at the proximity of the ciliary muscle or morespecifically, at the scleral spur for the interaction. The sensor cellconsists of two elements with chambers connected with the correspondingchambers of the accommodating cell. These elements of the sensor cellare placed externally and internally to the ciliary muscle fibers(scleral spur) to create differential pressure between the chambers ofthe sensor cell with muscle contraction or relaxation—pressure at theinternal to the muscle chamber increases and external to the musclechamber reduces with the muscle contraction and returns to the originalcondition with muscle relaxation.

The shape of the sensor cell of this embodiment consists of two plateswith each chamber situated inside each plate. Each plate has hardexterior shell and soft interior membrane to respond to the force fromthe ciliary muscle and transfer a small amount of material betweencorresponding chambers of the sensor cell and accommodating cell tochange the shape of the accommodating element separating the chambers inthe accommodating cell. Only small amount of material transfer, smallfraction of milliliter, is required to form diffractive surface for nearvision from refractive surface for far vision as shown in this exampleof the invention.

FIG. 13 shows the exterior view of the sensor cell in order toillustrate some specifics of the sensor cell in this example. Itincludes two ports each connecting with each chamber of the sensor cellto allow pressure adjustment between the chambers after in-vivoinstallation into the patient and connection with DiffractiveAccommodating Lens. This is in order to adjust for a proper pressurethreshold between the chambers to reliably switch between the opticalstates for far and near vision with the ciliary muscle contraction andrelaxation which may depends upon the patient physiology and sensor cellinstallation.

FIG. 14 demonstrates aphakic Diffractive Accommodating Lens of thisinvention which replaced the natural crystalline lens. The FIG. 12demonstrates the placement of sensor cell at the location of anteriortendon that includes scleral spur. Alternatively, it can be installed atthe posterior tendon at the area of ora serrata. The sensor cell isplaced with the exterior chamber being exterior to the ciliary muscleand the interior chamber to the interior to the ciliary muscle. The FIG.12 demonstrates two paths for connecting element: through the ciliarysulcus posterior to the iris or iridocorneal angle anterior to the iris.Later will involve an iridotomy by making a puncture-like openingthrough the iris without the removal of iris tissue for the connectingelement. The advantage of iridocorneal angle path is that it is moresimilar to the already developed glaucoma surgery technique thatinvolves glaucoma shunt installation.

FIG. 15 demonstrates Diffractive Accommodating Lens (DAL) of thisinvention which compliments a previously installed aphakic conventionIOL which is lacking Presbyopia correction. The DAL is placed in thecommonly acceptable position at the ciliary sulcus in front of thepreviously implanted conventional IOL. The sensor cell and itsconnection with the DAC is similar to one described in the FIG. 12.

FIG. 16 demonstrates phakic Diffractive Accommodating Lens (DAL) of thisinvention that does not involve a removal of the natural crystallinelens. The DAL is placed in the iridocorneal angle or by the irisfixation. The sensor cell and its connection through the iridocornealangle with the DAC is similar as one described in the FIG. 12.

FIG. 17 demonstrates corneal implant Diffractive Accommodating Lens(DAL) of this invention. The DAL of appropriate shape and thickness isplaced in the cornea and connected to the sensor cell installed asdescribed in the FIG. 12. The procedure does not require a penetrationinside the eye.

FIG. 18 demonstrates a front view of aphakic Diffractive AccommodatingLens (DAL) of this invention which replaced the natural crystalline lensand relies on vitreous pressure or capsular bag tension change forswitching between far and near vision. These environmental changescaused by ciliary muscle action affect the DAL directly without a needof sensor cell.

FIG. 19 demonstrates cross-section of the aphakic DiffractiveAccommodating Lens (DAL) of FIG. 16 which replaced the naturalcrystalline lens but relies on vitreous pressure or capsular bag tensionchange for switching between far and near vision.

FIG. 20, FIG. 21 and FIG. 22 demonstrate optical characteristics ofDiffractive Accommodating Lens of particular optical design in the eyein terms of longitudinal spherical aberration graphs (LSAs) at Far imageand Near images. Two optical designs for near vision are shown as theexamples.

FIG. 23 and FIG. 24 illustrate diffractive accommodating spectacles. TheDAL spectacles allow to maintain large range of field for both distanceand near vision and also to achieve automatic accommodation between farand near vision.

FIG. 25 illustrates diffractive accommodating spectacles with theaccommodating cell divided into two zones, one to produce near focus instressed condition and another to produce intermediate focus in stressedcondition.

FIG. 26 and FIG. 27 demonstrate Diffractive Accommodating Lensapplication to contact lenses. The diffractive accommodating contactlens can provide accommodation between far and near vision without aneed for the lens precise movement on the eye required for alternatingor segmented contact lens or without compromising image contrast andoverall image quality as in simultaneous vision multifocal contactlenses.

DETAILED DESCRIPTION

FIG. 1 illustrates a portion of eye anatomy related to the accommodationprocess. The ciliary body 100 has three basic functions: aqueousproduction and removal, accommodation, and the formation of vitreousmucopolysaccharide. The ciliary muscle initiates accommodating processand situates inside the ciliary body 100. The ciliary muscle containsthree types of fibers: longitudinal 110, radial 120 and circular 130fibers.

The accommodation function is the primary objective of this inventionand the first order is to describe the ciliary muscle including theiranatomy.

The ciliary body 100 is somewhat triangular in meridional sections andpresent circumferentially around the internal surface of the eye globe.It is narrower nasally (4.5-5.2 mm) than temporally (5.6-6.3 mm). Theanterior margin of the ciliary body 100 is at the scleral spur 150 isabout 1.5 mm posterior to the corneal limbus 160 in the horizontalmeridian and 2 mm posterior in the vertical meridian. Corneal limbas 160separates sclera 200 and cornea 240. Ciliary body 100 terminatesposteriorly at the ora serrata 170 where the eye retina starts and whichis approximately 7.5 to 8 min posterior to the corneal limbus 160temporally, 6.5 to 7 mm nasally, and 7 mm inferiorly and superiorly.

Interiorly and externally, the ciliary body 100 forms a part of theposterior portion of the anterior chamber angle. The iris 180 isattached to its anterior and internal surface. Internally, it lies freeand extends internally slightly anterior to the equator of thecrystalline lens 190. Externally, it is adjacent to the sclera 200 withthe perichoroidal space between the two. The internal surface of theciliary body 100 is adjacent to the vitreous 210. The space formed bythe posterior surface of the iris 180 and the internal and slightlyanterior projection of the anterior-most ciliary processes 140 is calledthe ciliary sulcus 220.

The greater part of ciliary muscle is composed of external longitudinalfibers 110 running anterior-posterior on the inner aspect of the sclera200 to insertion into the where muscle stars are produced referred to asepiscleral stars close to ora serrata 170. This muscle is attached tothe back of the eye via an elastic membrane at the suprachoroid (about 8mm behind the Embus 160) in the region of the ora serrata 170. Itscontraction pulls the ciliary body 100 forwards and inwards by 0.5 mmduring maximum accommodation. As a result, periphery of the vitreous 210is also compressed so that the lens 190 moves forward. The mechanism ofvitreous compression is used in some accommodating IOL design byCumming, U.S. Pat. No. 5,476,514 and others and is referenced in thisdisclosure as secondary accommodating effect.

The middle radial 120 and internal circular 130 fibers form a meshwork.The middle radial fibers 220 run obliquely to merge and attach to theciliary processes 140. The innermost edge of the ciliarly musclecontains primarily circular fibers 130. It appears that circular fibers130 run in a circle around the ciliary body 100 concentrically with theroot of iris 180. Their sphincter like action contracts the ciliary ringaround the lens 190 and thereby relaxing the anterior and posteriorzonules 230. The anterior portion of the radial and circular fibersproject anteriorly and centrally along a line approximately 45 degreesto the sclera plane. The ciliary body moves internally by about 0.34 mmand the equator of the capsule moves internally by about 0.25 mm withthe muscle contraction.

The architecture of all three types of fibers has some generalprinciples. All 3 are attached anteriorly at the ciliary tendon (scleralspur 150 and surrounding soft tissue) as Y shaped extensions with the Yinserting anteriorly into the tendon. The radial fibers 120 connect torelatively distant parts of the ciliary tendon and additional anteriorfiber attachment to the iris 180. The tension on Scleral Spur effectscorneal power so very slightly, less than 0.1 D and called in thisdisclosure as 3rd order accommodating effect. The uniqueness of thisinvention is to install a Sensor Cell described below at the area ofciliary tendon which has easy access. The sensor cell of this inventionis used to transfer the effects of ciliary muscle contraction andrelaxation in a form of pressure change to the accommodating cell ofthis invention situated inside the diffractive accommodating lens DAL inorder to switch its states between far and near vision.

The maximum force of contraction of the entire muscle (radial forceextended from ciliary muscle onto the lens 190) increases from 0.85×10⁻²N at age 15 to about from 1.3×10⁻² N at age 45 and then drops to aboutfrom 1.1×10⁻² N at age 55. The entire contraction force reaches themaximum (for accommodation of about 2.5 D) of 1.2×10⁻² N (≈1.2 g) at age43 and, importantly, the ciliary muscle action is maintained throughoutthe age thus maintaining the effectiveness of the Sensor Cell.

The aqueous production by ciliary processes 140 together with the flowof aqueous 250 to the trabecular meshwork 260 and Schleman's canal 270are essential for maintaining normal internal eye pressure andsignificant body of technology has been developed to treat the aqueousflow abnormality that lead to glaucoma. Different surgical techniquesand devices (glaucoma shuts, for instance) have been developed forplacement in the area of Schleman's canal 270. It has appeared that theapplication of the devices for glaucoma is practically at the intendedplacement of the sensor cell at the scleral spur 150 which is posteriorof Schleman's canal 270 by only 1 mm and surgical techniques developedfor glaucoma can be applied to the accommodating system (sensor cell andDAL) of this invention.

FIG. 2 describes a portion of a prior art ophthalmic device withdiffractive surface 300 with blazed periodic structure 350. It alsoexplains the optical principle used by accommodating cell of thisinvention for switching between far and near vision.

The FIG. 2 includes input light ray 320 refracted at the diffractionsurface blaze and creating diffraction orders indicated by thedirections 320 a, 320 b, 320 c, etc. along which the exited light canonly be channeled. In this case, direction of (+1)-order diffraction isshown by 320 a and (−1)-order diffraction by 320 c but there areinfinite orders of diffraction.

FIG. 2 incorporates an explanation of the “geometrical model” ofdiffractive lens by including blaze ray 330 as the ray corresponding tothe refraction of the input ray 320 as being theoretically refracted atthe blaze. It is imaginable ray in the geometrical model of diffractiveoptic and coinciding with a real ray in terms of creating the actualimage in the direction of the ray only if the blaze ray coincides withthe direction to a diffraction order. The direction of the blaze ray 330in the FIG. 2 differs from the direction of O-order diffraction 320 bdue to the different refraction angles of the rays at the base curve 340and surface relief or blaze structure 350. A particular blaze angle iscreated by the selection of the groove height or blaze materialthickness (h).

If the blaze material thickness (h) is zero than the blaze structure 350coincides with the base curve 340 and the lens becomes refractive type.If the blaze material thickness (h) increases to refract the blaze ray330 along, say, (−1)-order of diffraction 320 b as shown in the FIG. 2,the lens becomes a Kinoform with 100% efficiency at (−1)-orderdiffraction, i.e. theoretically, 100% of light passing through the lensis directed to (−1)-order diffraction. In the prefer embodiment of thediffractive accommodating lens design the state with zero blaze materialthickness is selected to create the optical power for Far vision (Farpower) and non-zero blaze material thickness is to direct most lightalong (−1)-order diffraction by the diffractive accommodating lens foroptical power for Near vision (Near power).

The periodic structure, i.e. radii of the diffraction grooves, definesthe separation between the diffraction orders. This periodic structureis shown as surface relief structure if blaze shape in the FIG. 2 wherethe geometrical model is applied to. The surface relief structure cantake different shape of the diffraction grooves. The periodic structuremay also be in the form of refractive index modulation structure wherethe thickness of the material layer of different refractive indexmodulates with certain period to produce diffraction orders.

FIG. 3 shows a simplest form of the Accommodating cell shape as arectangular disc of about 4-6 mm diameter D and about 0.10 to 0.3 mmthickness W. The accommodation cell is made of transparent materials andacts as a lens with optical axis 590. The accommodating cell diameteracts as the image forming zone of the lens. In general, theaccommodating cell may be curved to take a desirable shape.

The accommodating cell is situated inside the Diffractive AccommodatingLens or it may take a shape of the lens by including necessarycurvatures by its external surfaces.

FIG. 4 demonstrates cross-section of the accommodating cell 600 withoptical axis 590 in the relaxed state when ciliary muscle is relaxed.The accommodating cell 600 of this embodiment includes two chambers 640and 650 filled with optical fluids (silicone fluids, for instance)separated by the wall called accommodating element 610 that has theability to change its surface shape with a difference in pressurebetween the chambers 640 and 650. One chamber 640 filled with opticalfluid of matching refractive index to the accommodating element 610separating the chambers to make light passing between the accommodatingelement separating the chambers and the optical fluid of the chamber 640undisturbed by the surface shape facing this chamber 640. Optical fluidof non-matching refractive index fills the other chamber 650. As aresult, light refraction only takes place at the surface 560 facing thechamber 650. Chamber 640 is called optically transparent chamber (OTC)and chamber 650 is called optically active chamber (OAC). The FIG. 4demonstrates that the surface 560 facing the chamber 650 withnon-matching refractive index is smooth and continuous to formrefractive surface type per this preferred embodiment.

Construction of the accommodating cell in general can be to changepressure in optically transparent chamber first to drive the change ofthe shape of the accommodating element to change the states between farand near vision or in optically active chamber first or simultaneouslyin both chambers as it is explained below with interaction withdual-chamber Sensor Cell, for instance.

Exterior of chamber 640 is limited by the membrane 620 and the chamber650 is by the membrane 630. The accommodating element 610 consists ofaccommodating sub-elements 680, 690, 700, 710 and so on. The centralsub-element is shown as solid piece situated in contact with membranes620 and 630 at the center via corresponding pins 660 and 670 in order toassist with assembly of the accommodating cell and also to maintain theaccommodating cell shape integrity for both membranes 620 and 630.

The central sub-element is fairly small; a fraction of millimeter indiameter and its shape facing the chamber 650 may be either flat orcurved corresponding to the power for far, near or between far and near.In any case, it is too small to noticeably affect the overall imagequality for eye far or near image. All other sub-elements are shown withflat surface 560 facing chamber 650. The sub-elements 690 and 700 areseparated by substantially thinner material portion 570, which isrepeated for all other sub-elements outside the central sub-element 680.These circular material portions are thin enough to provide bending ofthe sub-elements in case of certain level of difference in pressurebetween the chambers 640 and 650. Another side of the sub-elementsindicated as 580 for sub-element 690 as the same as for others is alsothinner than the rest of each sub-element thickness to assist with eachsub-element bending.

The separation between the sub-elements and membrane 620 is of width Hlimiting the maximum bending of all sub-elements. The face 575 of thesub-element 690 facing the neighboring sub-element 700 is narrowedtowards its edge between face 575 and face 585 to prevent bending thesub-element 690 towards chamber 650. The same construction is applied toall other sub-elements. Thus, bending of each sub-element is restrictedtowards the chamber 640 by the maximum dimension H which is somewhere inthe range of 10-20 microns, depending upon the material refractiveindices of the accommodating element and not matching optical fluid andtargeted power difference between far and near vision. Below, thedisclosure offers the specific example of the accommodating elementconstruction.

All sub-elements have circular shapes around the optical axis 590.Though the chamber 640 is shown in the cross-section as being divided bythe sub-elements into sub-chambers, all these sub-chambers are connectedwith each other by the radial channels.

FIG. 5 demonstrates a cross-section of the accommodating cell 600 withoptical axis 590 in the stressed state when the ciliary muscle iscontracted. As a pressure in the chamber 650 increases because of someoptical fluid is squeezed into it by the accommodation action, thesub-elements 690, 700, 710 and so on bend at the thinnest places 720 andso on to create surface relief structure of the diffractive surface ofthe accommodating element 610. The maximum bending is limited to themagnitude H which is the width of the chamber 640 resulting in theequivalent groove height or blaze material thickness to produce theKinoform, i.e. to direct most of the available light in the direction of(−1)-order diffraction for near vision.

The accommodating element 610 between the chambers 640 and 650 takes ashape of surface relief of, more specifically, shape of blazes to formdiffractive grooves 740, 750, 760 and so on facing the chamber 650filled with non-matching with the material of the accommodating elementrefractive index. The diffractive surface relief heights (blaze materialthickness) is restricted by the geometry H of the accommodating elementto create the Kinoform with the focus for near vision, i.e. 100% oflight or most of the available light is directed to (−1)-orderdiffraction by the created diffractive surface relief surface of theaccommodating element 600.

The accommodating element 610 takes shape of blaze of groove height H ifthe difference in pressure between the chambers 640 and 650 exceedscertain threshold .DELTA.P. If the difference in pressure below thisthreshold .DELTA.P then the light split between far and near focisimilar to a multifocal diffractive lens. Nevertheless, the benefit ofdiffractive accommodating lens of this invention is that light splitoccurs only in stressed state for near vision where halo and glare isusually not the issue because of the presence of significant ambientlight required for near vision,

The refractive surface of the accommodating element 610 of FIG. 4 doesnot manifest diffractive grooves but, for generality, the refractivesurface is defined as the extreme condition of the surface reliefstructure of the diffractive surface of the accommodating element 610 ofFIG. 5 with surface relief structure height H equals zero. Thus, one cansay that the refractive surface of the accommodating element 610 of FIG.4 has the same periodic structure as the diffractive surface of theaccommodating element 610 of FIG. 5 but their height is zero. In generalterms, the diffractive surface of the accommodating element 610 iscalled surface-relief structure which is not limited to a particulargroove shape and the refractive surface 560 of the FIG. 4 is consideredas the special case of the surface-relief structure of the same periodbut zero height.

Theoretically, the created Kinoform directs 100% of light to near focus.Due to the construction restriction, the diffraction efficiency η⁻¹ at(−1)-order is reduced by the surface shape of the bent material portion720 and alike between all sub-elements:

$\begin{matrix}{\eta_{- 1} \approx \left( \frac{\Delta \; r^{\prime}}{\Delta \; r} \right)} & (1)\end{matrix}$

where Δr′ is reduced from the theoretical period Δr of groove equaled tothe width of the sub-element due to so called “shadowing”, in this caselight passing through 720 and alike is out of phase for constructiveinterference at near image from all sub-elements. The average groovewidth Δr is in the order of 0.1 mm and the width of thin materialportion 720 is about 10th of it dimension leading to a theoreticaldiffractive efficiency for near vision of about 90%.

The surface relief structure of the Accommodating element 610 isconstructed to produce the same single focus by all its sub-elements instressed condition of ocular implants and spectacle lens in order tomaximize the image quality. In case of a spectacle lens applicationwhere eye rotates and viewing through different portions of thespectacle lens, there is a benefit to divide the accommodating elementinto zones with different periods of surface relief structures of thezones. Under a stressed condition, the surface relief structure in eachzone direct light to different foci of each zone (−1)-order diffraction.Thus, one zone may be for near focus and another zone is forintermediate focus and both foci come into play simultaneously understressed condition.

FIG. 6 demonstrates cross-section of the accommodating cell 600′ withoptical axis 590′ in the relaxed state when ciliary muscle is relaxed.The accommodating cell 600′ of this embodiment includes two chambers640′ and 650′ where first chamber 640′ is filled with optical fluid(silicone fluids, for instance) and other chamber 650′ is connected tothe external medium of the ophthalmic lens. They are separated by theaccommodating element 610′ that has the ability to change its surfaceshape with a difference in pressure between the chambers 640′ and 650′.The chamber 640′ filled with optical fluid of matching refractive indexto the accommodating element 610′ separating the chambers to make lightpassing between the accommodating element separating the chambers andthe optical fluid of the chamber 640′ undisturbed by the surface shapefacing this chamber 640′. As a result, light refraction only takes placeat the surface 560′ facing the chamber 650′. Chamber 640′ is opticallytransparent chamber (OTC) and chamber 650′ is optically active chamber(OAC). The FIG. 6 demonstrates that the surface 560′ facing the chamber650′ is smooth and continuous to form refractive surface type per thispreferred embodiment.

Exterior of chamber 640′ is limited by the membrane 620′ and the chamber650′ is by the membrane 630′. The accommodating element 610′ consists ofaccommodating sub-elements 680′, 690′, 700′, 710′ and so on. The centralsub-element is shown as solid piece situated in contact with membranes620′ and 630′ at the center via corresponding pins 660′ and 670′ inorder to assist with assembly of the accommodating cell and also tomaintain the accommodating cell shape integrity for both membranes 620′and 630′.

The sub-elements 690′ and 700′ are separated by substantially thinnermaterial portion 570′, which is repeated for all other sub-elementsoutside the central sub-element 680′. These circular material portionsare thin enough to provide bending of the sub-elements in case ofcertain level of difference in pressure between the chambers 640′ and650′. Another side of the sub-elements indicated as 580′ for sub-element690′ as the same as for others is also thinner than the rest of eachsub-element thickness to assist with each sub-element bending.

The separation between the sub-elements and membrane 630′ is of width H′limiting the maximum bending of all sub-elements. The same constructionis applied to all other sub-elements. Thus, bending of each sub-elementis restricted towards the chamber 650′ by the maximum dimension H′ whichis somewhere in the range of few microns to about 20 microns, dependingupon the material refractive indices of the accommodating element andexternal medium and targeted power difference between far and nearvision.

All sub-elements have circular shapes around the optical axis 590′.Though the chamber 640′ is shown in the cross-section as being dividedby the sub-elements into sub-chambers, all these sub-chambers areconnected with each other by the radial channels.

FIG. 7 demonstrates a cross-section of the accommodating cell 600′ withoptical axis 590′ in the stressed state when the ciliary muscle iscontracted. As a pressure in the chamber 650′ increases, thesub-elements 690′, 700′, 710′ and so on bend at the thinnest places 720′and so on to create surface relief structure of the diffractive surfaceof the accommodating element 610′. The maximum bending is limited to themagnitude H′ which is the width of the chamber 650′ resulting in theequivalent groove height or blaze material thickness to produce theKinoform, i.e. to direct most of the available light in the direction of(−1)-order diffraction for near vision.

The accommodating element 610′ between the chambers 640′ and 650′ takesa shape of surface relief of, more specifically, shape of blazes to formdiffractive grooves 740′, 750′, 760′ and so on facing the chamber 650connected with external medium. The diffractive surface relief heights(blaze material thickness) is restricted by the geometry H′ of theaccommodating cell to create the Kinoform with the focus for nearvision, i.e. 100% of light or most of the available light is directed to(−1)-order diffraction by the created diffractive surface relief surfaceof the accommodating element 600′.

The surface relief structure of the Accommodating element 610′ isconstructed to produce the same single focus by all its sub-elements instressed condition of ocular implants and spectacle lens in order tomaximize the image quality. In case of a spectacle lens applicationwhere eye rotates and viewing through different portions of thespectacle lens, there is a benefit to divide the accommodating elementinto zones with different periods of surface relief structures of thezones. Under a stressed condition, the surface relief structure in eachzone direct light to different foci of each zone (−1)-order diffraction.Thus, one zone may be for near focus and another zone is forintermediate focus and both foci come into play simultaneously understressed condition.

FIG. 8 demonstrates assembly of the accommodating cell 600 of the FIG. 4consisting of three elements: front and back membranes 620 and 630 toform external walls of the chambers filled with optical fluids andaccommodating element 610 forming the wall between the chambers.

The accommodating element 610 consists of accommodating sub-elements;one sub-element 690 is pointed to on the FIG. 8. Each sub-elementincludes very thin portion 570 between the sub-elements and thin portion580 at the opposite side of the sub-element to assist with its bending.It also may include guides 770 and 780 for pins 660 and 670 to assistwith the assembly and to maintain shape integrity of the membranes 620and 640 during accommodating cell actions.

The elements of the accommodating cell can be made of commonly used inocular applications polymers and particularly elastomers (silicone,acrylic or within the variety of other materials).

The smallest features of the most delicate accommodating element of theaccommodating cell is in microns and can be accurately and inexpensivelyreproduced by vacuum casting or injection molding techniques. Inaddition, coating can be applied if the elements of the accommodatingcell are too thin to prevent permeability by optical fluids, forinstance, atomic layer of silver coating which is too thin to interferewith the light transmittance.

FIG. 9 illustrates front view of one of the embodiments of typicalconfiguration of intraocular lens 410 with optical axis 790 of lensoptic with the optic center O, with the peripheral optical edge 880,haptics or supporting elements 830 and 840 and the addition of theconnecting flexible element 820 attached to the accommodating cell 600situated inside the intraocular lens 410 of this embodiment and shown byits peripheral edge 900. Optical center “O” is a cross-section of theoptical axis 790 with the lens surface. This definition of the opticalcenter is used throughout this invention disclosure. The back element ofthe lens 410 shown by the peripheral optic edge 880 may includeperipheral wedge 890 for attaching the front element shown by itsperipheral edge 910 with accommodating cell situated between these twoelements.

The connecting element 820 is to connect the accommodating cell 600 thatchanges the optical state between far and near vision with the sensorcell that interacts with the ciliary muscle to transfer the forceresulted from the ciliary muscle contraction and relaxation into adifference in pressure between the chambers of the accommodating cell.The length of the connecting element 820 is about 6 mm which is adequateto connect sensor cell situated at the location of the ciliary tendon ofthe ciliary muscle and accommodating cell situated inside an intraocularlens.

Upon implantation of lens 410, sensor cell and connecting then by theconnecting element 820, there is a period of stabilization when thewound heals and capsule bag undergoes possible fibrosis and shrinkagethat may cause uncontrolled pressure on the implant 410 shifting imagingfrom far to near focus. In order to maintain far vision during thisperiod, a stabilizing chamber 825 can be part of the implantconstruction which tightens the connecting element 820 to prevent a flowof optical fluids in and from chambers of accommodating cell 600. Thestabilizing chamber 825 is filled with BSS by high enough pressure. Theoriginal state of the accommodating cell 600 set for far vision is thenmaintained because the optical fluids are uncompressible.

After the stabilization period when the capsular bag becomes relaxed,the stabilizing chamber 825 is pierced with Nd:YAG laser to release BSSand open up the connecting element 820 to allow optical fluids flowbetween the accommodating cell 600 and sensor cell.

This principle to use stabilizing chamber with BSS or any otherphysiologically neutral solution to maintain a desirable optical stateby the accommodating implant designed with microfluidic that can bepierced by a laser beam to restore the implant's dynamic state, can beapplied to any accommodating design that includes microfluidic action.

FIG. 10 shows the cross-section of the intraocular lens 410 with opticalaxis 790 as shown on the FIG. 7. It shows also one of the haptics 840.The FIG. 10 demonstrates the accommodating cell 600 situated inside theintraocular lens 410 with connecting element 820 attached to it at oneend 930 and the other end 870 of the connecting element is attached tothe opposite edge of the intraocular lens optic for its temporaryfixation during lens implantation inside the eye. This end 870 isseparated from the intraocular lens inside the eye for connection to thesensor cell.

The FIG. 8 demonstrates the stabilizing element 825 blocking theconnecting element 820 to prevent optical fluids to flow in and out ofthe accommodating cell 600 in order to maintain far vision duringstabilizing period.

The lens 410 consists of front elements 800 with the front surface 850and back element 810 with the back surface 860. The front element 800may be attached to the back element 810 via the wedge mechanism 920 asan inexpensive assembly of the whole lens 410.

FIG. 11 illustrates assembly of the intraocular lens 410 shown on theFIGS. 9 and 10. The intraocular lens of this particular embodimentconsists of three elements: front element 800 which can be attached tothe back element 810 at the front wedge 920 and the accommodating cell600 placed between them. Simplest plano-convex shape of the frontelement enables making an inexpensive variation of its opticalcharacteristics, such as a variety of dioptric powers, asphericity andtoricity for astigmatism correction, by shaping the front surface 850.Back element 810 of this embodiment incorporates also haptics 830 and840 and is of a more complex shape and is less variable element of theintraocular lens manufacturing. Accommodating cell 600 is situated inthe hollow at the front of the back element 810 in contact with surface950 and is secured inside the lens 410 by front element 800 to allow theoverall intraocular lens 410 to take a conventional shape of a typicalnon-accommodating lens and, therefore, to utilize conventionimplantation techniques.

The connecting element 820 is permanently attached to the accommodatingcell at 930 and secured to the lens 410 at the opposite end 870 for thelens 410 implantation and then the end 870 is attached to the sensorcell.

FIG. 12 illustrates the connection between sensor cell 605 andaccommodating cell 600. The connecting element 820 is about 6 mm inlength which is adequate to place the sensor cell at the proximity ofthe ciliary muscle for the interaction and accommodating cell to besituated inside the Diffractive Accommodating Lens of this invention.

A dual chamber sensor cell 605 per this example consists of two plates360 and 370 with chambers 980 or 1010 inside of each plate connectedwith the corresponding chambers 640 or 650 of the accommodating cell600. The plates 360 and 370 of the sensor cell 605 are placed externallyand internally to the ciliary muscle fibers with the ciliary tendonsituated in between to create a differential pressure between thechambers 980 and 1010 of the sensor cell 605 with muscle contraction andrelaxation. Pressure at the internal to the muscle chamber 1010 in theplate 370 increases and external to the muscle chamber 980 at the plate360 reduces with the muscle contraction when the ciliary muscle movesinward and the pressure in the chambers 360 and 370 returns back to theinitial state with ciliary muscle relaxation.

Each plate 360 or 370 has hard exterior shell 960 or 990 and softinterior membrane 970 or 1000 to respond to the force exerted by theciliary muscle and then to transfer the difference in pressure betweenthe sensor cell chambers 980 and 1010 to the difference in pressurebetween the accommodating cell chambers 640 and 650 via the channels1020 and 1030 of the connecting element 820.

The corresponding change in pressure between the chambers 640 and 650 ofthe accommodating cell 600 switches the optical states of the eyebetween far vision with ciliary muscle relaxation and near vision withciliary muscle contraction. The pressure threshold is set at the sensorcell 605 between these two corresponding levels of pressure for areliable change in states of the accommodating cell between far and nearvision.

FIG. 13 illustrates some specifies of the dual chamber sensor cell 605exterior views facing outside the eye, i.e. front view of the plate 360with the chamber 980 inside. The other chamber 1010 is in the internalplate 370. The exterior of the sensor cell 605 is shown with two ports1040 and 1050 each connected to each chamber 980 or 1010 to allowin-vivo pressure adjustment between the chambers of the sensor cellafter the installation of the sensor cell, Diffractive AccommodatingLens and their connecting after the surgery. This is in order to adjustfor a proper pressure threshold between the chambers 640 and 650 of theaccommodating cell to reliably switching between the optical states offar and near vision with contraction and relaxation of the ciliarymuscle of the patient. The adjustment might be beneficial due toindividual variation in ciliary muscle action and sensor cell positions.

The sensor cell can be of different shape and construction and have onechamber with the fluid to interact with the ciliary muscle contractionto transfer the resulted force to the accommodating cell to switch fromfar to near vision.

FIG. 14 demonstrates aphakic Diffractive Accommodating Lens 410 of thisinvention which replaces the natural crystalline lens and consisting ofoptic 400 and haptics 420. The DAL 410 is shown as being placed insidethe capsular bag 290. The FIG. 14 demonstrates the placement of thesensor cell with external plate 360 and internal plate 370 around theanterior tendon of the ciliary muscle that includes scleral spur 370.The sensor cell is placed with the exterior plate 360 with its theexterior chamber being exterior to the ciliary muscle 110, 120, 130 andthe interior plate 370 with its interior chamber to the interior to theciliary muscle 110, 120, 130. The FIG. 14 demonstrates two paths of theconnecting element 430 between the sensor cell and accommodating cell:through the ciliary sulcus 220 posterior to the iris 180 or iridocornealangle 280 anterior of the iris 180, path 440. Later will involve aniridotomy by making a puncture-like opening through the iris without theremoval of iris tissue for the connecting element to go through the iris180. The advantage of iridocorneal angle path 440 is that it is moresimilar to the already developed glaucoma surgery technique thatinvolves a glaucoma shunt installation.

FIG. 15 demonstrates Diffractive Accommodating Lens (DAL) 460 of thisinvention which compliments a previously installed aphakic conventionIOL 450. The DAL 460 includes haptics 470 placed in the commonly usedposition at the ciliary sulcus 220 in front of the previously implantedconventional IOL 450. The sensor cell with plates 360 and 370 is similarto those described in the FIG. 14. The connection 430 of the sensor celland DAC 460 is also may have two paths, one through the ciliary sulcus220 and another through iridocorneal angle 280 to the DAL 460 and aresimilar to those described in the FIG. 14.

FIG. 16 demonstrates phakic Diffractive Accommodating Lens (DAL) 500 ofthis invention that does not involved a removal of a natural crystallinelens 190. The DAL 500 is shown as being placed with its haptics 510 inthe iridocorneal angle 280 but the phakic DAL can also be iris fixated,i.e. the lens haptics are attached to the iris 180, or phakic DAC can beplaced behind the iris 180 and in front of the crystalline lens 190. Thesensor cell with plates 360 and 370 is similar to those described in theFIG. 14. The sensor cell and its connection element 520 through theiridocorneal angle 280 with the DAC 500 is similar as one described inthe FIG. 14.

FIG. 17 demonstrates corneal implant Diffractive Accommodating Lens(DAL) 530 of this invention which is placed in the cornea 240. The DAL530 of appropriate shape to match the corneal shape and thickness isplaced in the cornea 240 and connected to the sensor cell with plates360 and 370 is similar to those described in the FIG. 14. The DAL 530 isconnected with sensor cell with connection element 540 that goes overthe cornea 240. The procedure does not require a penetration inside theeye.

FIG. 18 illustrates another option of the aphakic diffractiveaccommodating lens 1100 operation that changes its optical statesbetween far and near vision by direct effect of the vitreous pressure orcapsular bag tension. As a secondary accommodating effect, ciliarymuscle contraction changes choroid tension thus increases vitreouspressure causing crystalline lens-zonule complex to move forward. Theeffect is also observed with the crystalline lens replacement by aphakicIOL which can move by about 0.1-0.2 mm either forward or even in someinstances, backward. Due to diffractive design of the diffractiveaccommodating lens, a direction of movement is irrelevant as long asthere is a change in vitreous pressure and the pressure threshold of theaccommodating cell is set within the range of the vitreous pressurevariation.

The DAL 1100 consists of front element 1110, back element 1140 andaccommodating cell 1160 between them. Front element 1110 incorporatessupporting members or haptics 1120 and 1130 to secure lens 1100 positioninside the eye. Back element 1140 is attached to the front element 1110via sub-chambers 1190, 1200, 1210 and 1220 (could be a differentsub-chamber design) connected with the accommodating cell 1160 chamberwith optical fluid of non-matching refractive index, optically activechamber, with accommodating element material to allow fluid to travelbetween them. The other optically transparent chamber with matchingrefractive index is connected with sub-chamber 1180 supported by aflexible membrane to allow its volume to change if the optical fluid issqueezed out from the connecting chamber of the accommodating cell bythe pressure from the sub-elements 1190 etc., due to external forcessuch from the vitreous, for instance. The pressure might be required tobe adjusted for relaxed state post-operatively after the healing andlens stabilization inside the capsular bag. This might be performedthrough a chamber port using a needle.

A DAL may only include optically transparent chamber and function ofoptically active chamber is taken by the aqueous humour. In this caseaccommodating element is facing the aqueous humour one side andoptically transparent chamber on another.

FIG. 19 demonstrates a cross-section of the diffractive accommodatinglens 1100 of the FIG. 18. The lens consists of front element 1110 thatincludes haptic with one haptic 1130 shown on the FIG. 19. Back element1140 is held onto the front element 1110 by the wedge structure 1170 andattached to the front element 1110 via sub-chambers 1190 and 1200. Thesesub-chambers can be of different number and shape.

Vitreous pressure shown by 1239 is exerted on the back element 1140 withvariable magnitudes depending on the ciliary muscle contraction andrelaxation as well as the lens 1100 fixation inside the eye. This inturn, changes the pressure on the sub-elements 1190, 1200 and others,transferring small amount of the optical fluid into the accommodatingcell 1160 chamber with non-matching refractive index. This in turnchanges the shape of the surface relief of the accommodating elementfacing non-matching refractive index chamber by transferring a smallamount of optical fluid from the matching refractive index chamber intothe corresponding sub-chamber 1180 by flexing its membrane. Sub-chamber1180 is shown as a ring structure around the accommodating cell externaledge but it can be of a different shape and location with maintainingthe principle of operation of changing accommodating element surfaceshape from refractive to diffractive or between orders of diffraction toredirecting light between far and near foci.

The ophthalmic lens described by the FIG. 19 can be substantiallysimplified with the use of the accommodating cell 600′ described byFIGS. 6 and 7. The sub-chambers 1190 and so on are replaced bysub-chambers connected to the optically transparent chamber (OTC) filledwith optical fluid of matching refractive index with accommodatingelement and the optically active chamber is connected to the exteriormedium such as aqueous humour. The amount of fluid transfer fromsub-chambers to OTC may control the bending of the accommodatingelements that creates surface relief structure. No need for sub-chambers1180 and so on connected with the optically active chamber of theaccommodating cell.

Upon implantation the lens 1100 into the capsular bag, there is a fewmonths period when the capsular bag may shrink and change tension on thelens 1100 impacting its relaxed state for far vision. One option tohandle this period is to include so called, stabilizing sub-chamber 1185shown as narrow circular shape in this case separating the front 1110and back 1140 elements and filled with BSS, for instance. Thestabilizing sub-chamber 1185 maintains stability of the lens 1100 duringthis initial post-operative period by preventing a dynamic change in theoptical state until the ocular condition becomes stable. Patientmaintains normal Far vision equivalent to any conventional monofocallens during this period. After the ocular condition is stabilized, thestabilizing sub-chamber 1185 is punctured with a Nd:YAG laser beam, forinstance, allowing BSS to be removed into aqueous thus reversing thelens 1100 to the dynamic condition to enabling it to change betweenrelaxed state for Far vision and stressed states for Near vision withabsence and presence of accommodating force. Only a small amount ofoptical fluid, small fraction of milliliter, is transferred in and fromthe corresponding chambers that involved in changing the shape of theaccommodating surface that separates both chambers of the accommodatingcell 1160 and switches between far and near vision. The process does notrely on a lens forward movement as with other accommodating IOLs butonly on a pressure change required for material transfer in the chambersbut only requires that back element 1140 and front element 1110 aresqueezed together by about 10-20 microns by the action of ciliarymuscle, choroid and vitreous. The lens 1100 itself may move forward orbackward during this process which is likely not to exceed a smallfraction of millimeter.

The sub-chambers 1200 the diffractive accommodating lens may havetransferred to the sensor cell installed to interact with the ciliarymuscle directly. In this case, the sensor cell has only one chamber withthe fluid and some function of the other chamber described above istaken by the sub-chamber 1180.

If the diffraction accommodating lens design relies on changes of thecapsular bag tension, then the construction of the accommodating cellmust be different from 600 or 1160 above by providing near vision at theresting state of the capsular bag and far vision at the increasedtension of the capsular bag.

The diffractive accommodating lens can be also applied to dual-lenssystem, U.S. Pat. No. 7,452,378 that relies on the capsular bag actionto change optical states between far and near vision. In this case, theaccommodating element is to provide far vision in stressed state andnear vision in relaxed state to follow the capsular bag actions which isaccomplished by either to have diffractive surface with (−1)-orderdiffraction at relaxed state (near vision) and refractive optic instressed state (far vision), or refractive optic in the relaxed state(near vision) and diffractive surface with (+1)-order diffraction instressed state (far vision).

FIG. 20 provides a Longitudinal Spherical Aberration at Far image formedby the Diffractive Accommodating Lenses DAL 1 and DAL 2 per thespecifications listed in the Tables 1 and 2 as being examples of theinvention.

TABLE 1 Eye model specifications where Diffractive Accommodating Lenses1 and 2 were analyzed. Dimension in mm; Optical Characteristicsrefractive index Cornea: Anterior surface radius 7.8 Refractive index1.377 Conic constant (asphericity Q) Nominal Q = −0.26 Posterior surfaceradius (mm) 6.5 Central thickness (mm) 0.55 Aperture stop or pupilposition 3.55 from posterior corneal surface (mm) Aqueous refractiveindex 1.3374 Vitreous refractive index 1.336

TABLE 2 Overall Specifications of Diffractive Accommodating Lens 1 and2. Dimension in mm; Optical Characteristics refractive index Power (D)21.0  Front element front surface vertex 17.55; bi-sign aspheric(*)radius material Acrylic, 1.489 thickness 0.30 back surface radius flatAccommodating Cell plano-parallel plate Acrylic, 1.489; 0.1 mm thickChamber A-E Optical fluid, 1.433 Switchable Element Silicone, 1.433; 0.1mm (SE) thick Chamber A-I Optical fluid, 1.403; 0.05 mm thickplano-parallel plate Acrylic, 1.489; 0.1 mm thick Back element frontsurface radius flat material Acrylic, 1.489 thickness 0.60 back surfaceradius −8.01  (*)Bi-sign aspheric has been disclosed by Portney in U.S.patent application No. 12/415,742. Aspheric coefficients of the frontsurface referenced to in the Table 2 are: −0.0015 at r⁴, 0.000172 at r⁶,0.00000446 at r⁸ and 0.000006 at r¹⁰.

The LSAs of Far images of DAL 1 and DAL 2 are the same because therefractive specifications of both lenses are the same. The LSAdemonstrates positive spherical aberration for up to about 1 mm from thelens center and negative spherical aberration outside 1 mm distancewhich is the characteristic of bi-sign asphericity.

The surface for far vision can be also made with a power variation toincrease depth of focus at far. For instance, to have higher power atthe center and then progressively reduced power to create negative powerslop known as increasing depth of focus. The power progressive may be upto 1 D with only marginal impact on image quality but to reducesensitivity to residual refractive error.

FIG. 21 and FIG. 22 provide Longitudinal Spherical Aberrations at Nearimages by the Diffractive Accommodating Lenses DAL 1 and DAL 2 producedat (−1)-order diffraction per the specifications of Eye model,Diffractive Accommodating Lenses 1 and 2 provided in the Tables 1 and 2.The surface of the accommodating element facing OAC acting as imagingzone that switches between far and near vision is placed within about 4mm diameter as shown on the Table 3 below. The LSA graphs show near LSAwithin this diameter and portion of far LSA outside 4 mm diameter as theLSA graphs is shown for 5 mm diameter on the FIGS. 19 and 20 and thuscapturing some of far LSA close to 5 mm diameter (2.5 mm distance fromthe lens optical center),

DAL 1 includes only small amount of spherical aberration in the (−1)order diffraction to produce close to spherical wavefront in creatingnear retinal image at 36 cm of near viewing distance. DAL 2 includes asignificant amount of spherical aberration in the (−1)-order diffractionto create retinal image from a near object placed not only around 36 cmviewing distance as in DAL 1 but at up to about 27 cm of near viewingdistance, i.e. to offer the increased depth of focus at near of about 1D. The increase in depth of focus at near is demonstrated by thecorresponding LSA shape on the FIG. 20 which starts at more near focusat the lens center and gradually shifts farther away to create anegative slope of the power graph. The extension of the range of visiontowards closer near is beneficial as there is a natural tendency tobring a near material closer to the eyes to observe finer details. Theincreased depth of focus of about 1 D at near may be shifted tointermediate vision by providing a range of vision from about 50 cm atintermediate to 36 cm at near. This is to expend the effectiveness ofthe diffractive accommodating lens from far and near to includeintermediate vision.

Specifications of the diffractive surfaces of the Accommodating cellswith small amount of spherical aberration for near image (DAL 1) andlarge amount of spherical aberration to extend depth of focus at imageby (−1)-order diffraction (DAL 2) are provided in the Table 3.

TABLE 3 Specification of the near diffractive state of (−1)-orderdiffraction of the Accommodating cells of the Diffractive AccommodatingLens DAL 1 and DAL 2. Per materials specified of Table 2 the diffractiveH = 0.0183 mm to create Kinoform in grooves heights (blaze materialthickness) are constant compressed state of the Accommodating Cell Phasecoefficients (radians) a_(i) of the Phase Function Φ⁻¹(r_(i)) per Eq. 3r r² r⁴ r⁶ DAL 1 (small spherical aberration) 0.231 20.968 1.116 −0.23DAL 2 (large spherical aberration) 0.168 31.867 −4.215 0.340 Grooveradii (mm) 1 2 3 4 5 6 7 8 9 10 11 12 13 DAL 1 0.538 0.738 0.925 1.0651.187 1.298 1.400 1.496 1.586 1.673 1.758 1.841 1.923 DAL 2 0.447 0.6420.799 0.937 1.065 1.187 1.305 1.422 1.537 1.653 1.768 1.881 1.981

The groove height H is to provide 100% diffraction efficiency for(−1)-order diffraction or at least to direct most of the available lightto near focus, i.e. the Diffraction Accommodating Lens in thecorresponding diffractive state becomes the Kinoform. If groove heightis only a fraction of H because a difference in pressure between thechambers is below the threshold, the DAL becomes a multifocaldiffractive lens that split light between Far and Near foci. Thecorresponding vision is only for near because of the presence of someaccommodating force which only occurs for near vision. It takes only toachieve 40% of H for a grooves height (maximum height for Kinoform) inorder to direct 30% of light to Near focus and achieve sufficient nearvision. In case of the example on the table 3, it takes 7 microns ormore of grooves height to direct 30% or more of total light to Nearfocus.

Diffractive Accommodating Lens DAL 1 changes between two distinct fociof Far image demonstrated by far LSA in the FIG. 18 and Near imagedemonstrated by near LSA in the FIG. 21. Depth of focus or progressivefoci feature at near can be increased as shown in DAL 2 by modificationof the phase coefficients for (−1) order diffraction to includespherical aberration that spreads light along the optical axis at thenear image either to improve near close up or improve intermediatevision capability in addition to near. This extension of depth of focusat (−1)-order diffraction is accomplished independently of the Far imageLSA.

Another option to introduce multiple foci (near and intermediate) instressed condition is to use multi-zone option, i.e. to divide theaccommodating element into zones that under stress condition producesurface relief of different periodic structure resulting in differentfoci of (−1)-order diffraction of each zone. This way one zone, centralfor instance, may manifest intermediate focus and peripheral annuluszone to provide near foci or vice versa. Similar multi-zonal option canbe also applied to the switchable diffractive surface that is based onthe refractive index change where zones have different refractive indexamplitudes.

The near focus of DAL 1 and DAL2 can be in the range that corresponds tointermediate vision and for generality the meaning of near focusreferenced in this invention also includes intermediate focus, i.e. anyfocus produced by the accommodating cell in stressed state over the farfocus produced in the relaxed state.

The result of the depth of focus increase at (−1)-order of diffractionfor DAL 2 involves the change in the diffraction grooves shape which isillustrated by the difference in groove radii between DAL 1 and DAL2.The grooves radii of DAL 1 with small amount of spherical aberration ispractically equivalent the grooves radii defined by the paraxialapproximation of the Equation 1. Both DAL 1 and 2 include 13 grooveswithin about 4 mm diameter with central two grooves radii DAL 2 beingsubstantially smaller the corresponding grooves in DAL 1 and also by theradius of a more peripheral groove of DAL 2 reaching a similar magnitudeas the radius of the same groove order in DAL1, on 11th groove in theTable 3 of this example. Substantially smaller in general means about10% of more smaller. Substantially similar usually means within.+−0.10%. The radii of further grooves of DAL 2 then may exceed theradii of the corresponding grooves of DAL 1. This comparison between thegrooves of any diffractive lenses that produces small amount ofspherical wavefront (DAL 1) with the radii defined by the paraxial formof the Equation 1 and wavefront with extended spherical aberration thatincreased depth of focus (DAL 2) is applied to the same orders ofdiffraction and the same image positions defined by the diffractionorder focal length.

In case of an annular zone with progressive foci feature, the radii ofcentral grooves reference to the grooves starting at the internal sideof the annular zone, i.e. a reference to “central grooves” includescentral grooves of a zone that includes optical center of the lens or anannular zone.

Similar phase coefficients modification to enhance depth of focus atnear can be applied to monofocal diffractive non-accommodating lens,multifocal diffractive optics where light is split between far and nearfoci and near image is formed, for example, by (−1)-order diffractionand switchable diffractive surface that is based on the change in therefractive index modulation. Appropriate phase coefficients can beapplied to the multifocal diffractive optic, for instance, to lead tosimilar diffractive grooves shape change from the one producingspherical wavefront to result in the increase in depth of focus for(−1)-order diffraction. The result will be the same correlation betweenthe diffractive grooves as those in comparing DAL 1 as defined by theparaxial form of the Equation 1 and DAL 2 in the Table 3.

The difference between a DAL and corresponding multifocal optic would begrooves height or blaze material thickness in case of blaze grooves: thegrooves heights in multifocal optic is to split light between far andnear images and in DAL is to direct most of the available light to thediffractive focus.

Spherical aberration of Far image can also be expended to enhance depthof focus at far towards intermediate independently of the near imagedepth of focus extension. This can be accomplished by modifying at leastone of the refractive surfaces of the Diffractive Accommodating Lensincluding the refractive surface of the Accommodating Cell formed in thestate of Far vision shown in this particular embodiment.

FIG. 23 and FIG. 24 illustrate diffractive accommodating lens forspectacles. Almost universally, the series of front surface base curvesto cover the entire spectacles prescription range is used. This systemreduces lens inventory and eliminates the need for a different basecurve for every possible prescription. Sets of semi-finished blanks,with front curves varying in steps, are stocked in local opticallaboratories, and charts or computer programs show laboratory personnelwhich blank should be used for each prescription. The system wasdeveloped from the ability to have spectacle lens bending (combinationof front and back surface curvatures) that limits power error andoblique astigmatism error with eye rotation and viewing throughdifferent area of the spectacle lens. Eye rotation is usually up to 30degrees or even 40 degrees from the optical axis on each side of thespectacle lens optical center.

The disclosed Diffractive Accommodating Lens for spectacles 1300 isbuilt around the same system of front base curves by addingAccommodating Cell described above and shaped it similarly to the basesurface onto the front base surface of the single vision spectacle lens,1310 and 1320. This is one of the embodiments but the design is notlimited to this particular description as the accommodating cell may beeither add-on or as the insert. The back surface of the lens may includespherical and tone surface equivalent to single focus prescription ofthe same wearer of the glasses.

The Accommodating Cell of the Diffractive Accommodating Lens may includetwo chambers OTC and OAC or only one chamber OTC if the surface reliefstructure of the Accommodating Element faces the air which acts as OAC.In later case it is desirable for the surface relief structure to facethe base surface for its protection. The front membrane of theAccommodating Cell facing the exterior of the lens can be made thickenough to maintain Accommodating Cell integrity during lens cleaning.

The chambers of the Accommodating Element are connected to the controlmechanism 1340 consisting of two chambers each connected to thecorresponding chamber of the Accommodating Cell and separated by themoving separator connected to the nub 1350. The nub 1350 can be moved bethe wearer from one end to another to push the optical fluid in thecontrol mechanism 1340 in and out of the corresponding AccommodatingCell chambers in order to change Accommodating Cell states between farand near vision. The mechanism arrangement can be more conspicuous byplacing it in the skull temple 1370.

The near vision state of the accommodating cell is demonstrated on theFIG. 24 by the non zero height diffractive grooves 1410 and 1420centered at the near vision centers at both spectacle lenses placedbelow the corresponding far vision centered 1415 and 1425 whichpractically coincide with optical centers of the correspondingspectacles lenses. The nub 1350 is shown at its left position for farvision in the FIG. 23 and right position for near vision in the FIG. 24.The Accommodating cell of the lens at the other side of the spectacles1310 is also connected to the control mechanism 1340 via line 1360 beconnecting element as a tube passing through the bridge 1380 and alsothe nose pad 1390 depending upon the frame construction. This is toallow switching between far and near vision in both spectacle lensessimultaneously.

The diffractive grooves 1400 are optically designed to minimize powerand oblique astigmatism errors for near vision with eye rotation withincomfortable field of about 15-30 degrees range in different directionsfrom the near vision optical center located at the lower portion of eachspectacle lent and closer to the middle of spectacles than the opticalcenter of each lens that considers with far vision center.

The surface relief structure of the Accommodating Cell may havemulti-order diffraction where the phase period between the grooves isscaled up by the multiple factors, for instance by factor of 4-6. Thebenefit of the multi-order diffraction is the reduced chromaticaberration which is particularly importance for spectacle lenses wherethe control of transverse chromatic aberration raised with eye rotationis important.

The major issue with present day glasses for Presbyopia is the inabilityto see things that are close or intermediate, but straight ahead. TheDAL for spectacles allows addressing this issue by expending the areafor far and near vision by switching between different states. The lensalso allows addressing intermediate vision in three options:

(A) Trifocal arrangement to use +1-order diffraction for far, zero-orderfor intermediate and (−1) order for near or superposition of twoperiodicities of different add powers. There is the ability for precisecontrol of optical fluid in and out of the accommodating cell chamber toswitch between not only two but three diffraction orders. For instance,by removing the precise amount of fluid form the OAC, the accommodatingelement is bent in opposite direction from the previously explained(−1)-order diffraction to produce +1-order diffraction, and also byinjecting the precise amount of fluid into the OAC to produce (−1) orderdiffraction. In this case, the relaxed state would be for intermediatevision.

(B) Another option is to include the near vision with progressivediffractive design as explained by the FIG. 22. In this case, theintermediate power between far and near range covers the center of thelens to allow the wearer to look straight ahead for intermediate,computer screen, for instance.

(C) The third option is to divide the accommodating element into zonesof different periodic structures thus the separations betweendiffraction orders are different between the zones. It means theyproduce different foci for (−1)-order diffraction as explained by thespecifications to the FIG. 5 or 7. Near zone, i.e. zone that producesshorter focal length by its (−1)-order diffraction for near and it isplaced at the center of near vision below the optical center of thespectacle lens that concedes with the center for far vision. Peripheralzone, i.e. zone that produces longer focal length by (−1)-orderdiffraction for intermediate includes optical center of the spectaclelens to allow wearer to look straight ahead onto intermediate objectsuch as a computer screen, for instance. Both zones may take large areasof the spectacle lens to allow for a comfortable field because theyreplace far power area by switching the accommodating element and notjust complimenting the area of far vision as in conventional bifocals,trifocals and progressive glasses.

FIG. 25 illustrates a preferred embodiment of spectacle lens to providefar vision in one optical state and another state is a combination of(B) and (C) options described under the FIGS. 23 and 24 above where theaccommodating cell is divided into two zones in the activated opticalstate, central zone around 1410′ and 1420′ to produce near focus instressed condition and peripheral around optical centers 1415′ and 1425′of the spectacle lenses to produce intermediate focus. The correspondingmultizone structure of different periodic structures of the diffractivegrooves creates different foci for (−1)-order diffraction betweendifferent zones. The imaginable lines separating the zones are shown as1430 and 1435 to illustrate the location of near focus zone andintermediate focus zone.

A change in pressure to switch between different states of surfacerelief periodic structure heights can be accomplished only mechanicallywith optical fluid transfer to and out of the optical transparentchanger but also electronically by changing magnetic or electricalstates of the accommodating element and membranes. For instance,changing the magnetic states of the accommodating element and membraneforming the chamber into opposite or the same polarities would increaseor reduce pressure between the accommodating element and the membraneforcing the accommodating element to change the surface relief structureheight and, therefore, redirecting light from one diffractive order toanother (including zero order created by refractive surface).

The intermediate annular zone includes progressive foci change as shownunder FIG. 22 in reference to DAL 2 but for the annular zone. Thisprogressive change in foci is from intermediate at 1415′ and 1425′ withfoci reduction towards lines 1430 and 1436 to the level of near focus isin order to have a smooth foci transition from the peripheralintermediate vision zone and central near vision zone of theaccommodating cell thus avoiding an image jump common with abrupt focichange when the eye moves through this abrupt focus change. Theperipheral zones of the intermediate focus of the accommodating cells ofleft and right spectacles lenses includes corresponding optical centers1415′ and 1425′ to allow the wearer to look onto intermediate objectstraight ahead without tilting the head or training eyes to look througha specific area of the spectacle lens.

Multizone structure of different periodic structures of the diffractivegrooves that results in different foci for (−1)-order diffractionbetween different zones can be further expanded to be used as indicatorof the optical state of the spectacles. Additional zone is placed at theright periphery of right spectacle lens and left periphery of the leftspectacle lens. The surface relief periodic structure for (−1)-orderdiffraction of this third zone has substantially smaller periods thannear zone thus producing focus that is out of focus from retinalimaging. Therefore, the corresponding zone does not produce imaging forobject at any distance, it effectively reduces the field of thespectacle lens in horizontal plane. This can be used as an indicator tothe wearer in watt state his or her spectacles are—in relaxed state forfar vision or stressed state for near vision.

The principle of multizone structure that includes different zones ofperiodic structure of the diffractive grooves producing different focifor (−1)-order diffraction at different zones manifested in stressedstate may be applied to the spectacle lens with refractive indexmodulation as the improvement over the switchable lens described by Liand his colleagues and referenced to above. In this case the spectaclelens includes zones of different refractive index amplitudes. Forinstance, the spectacle lens produce far vision with refractive surfaceand near vision with non-zero diffractive order created by refractiveindex modulation from the original refractive surface and thediffractive surface is divided into at least two zones of differentperiodic structure to produce different focus positions for the samenon-zero diffractive order simultaneously such as near and intermediatefoci. The improvement may also include a foci transition betweenintermediate vision zone and near vision zone to avoid image jump.

System for automated switching between far and near vision can be alsoadded to the Diffractive Accommodating Lens by including gaze distancedetection. Gaze distance detection includes a combination ofemitter-sensors for infrared radiation placed at the spectacle lens orspectacles frame. It is based on the measurement of convergence anglebetween line of sights of right and left eyes from which the objectdistance is calculated. The light of sights are measures by detectingthe reflection off the corneas or pupil tracking or by more accuratemethods such as a comparison of the reflection from front cornealsurface with either the pupil position or 4th Purkinje image (reflectionfrom back surface of the eye's lens). One of the emitter-sensors isshown as 1330 and the FIGS. 23 and 24 to demonstrate one of threeemitter-sensors per each spectacle right and left sides to applytriangulation.

The signal from the sensors is passed to the microprocessor placed inthe skull temple 1370 to calculate the gaze distance to the viewingobject. As the distance lies within a near range, the correspondingsignal is sent to the electronic control mechanism placed in place of1340. It can be a micro solenoid acting as toddle switch to movearmature that pushes the optical fluid similar to the described abovemechanical control mechanism 1340. The manual override might be stillincluded.

FIG. 26 and FIG. 27 demonstrate Diffractive Accommodating Lensapplication to contact lenses. The design utilizes a principle ofbifocal segmented lens where the lens rides up pushed by the lower lidwhen the wearer looks down to look through the lower near segment of thelens. The lens rides down by its gravity when the wearer looks up tolook through the distance segment of the lens. The key point is that thelower lid applies pressure to the lens to ride it up which is used tocontrol switching between far and near vision of the DiffractiveAccommodating Lens 1450.

The lens 1450 is facing by front surface 1470 in the FIG. 23 and theAccommodating Cell 1500 is represented by the diffractive grooves 1460.Per the FIG. 26, the chamber 1480 filled with optical fluid is pressuredby the lower lid when the wearer looks down. Similar to a segmentedlens, the lens 1450 utilized the weighted bevel at the bottom of thelens, 1510 with the chamber 1480 inside it to minimize the lensrotation. The back surface 1490 shape can be maintained similar to onein a typical bifocal segmented lens.

The contact lens can be also constructed with only optically transparentchamber and the air at the front surface of the lens or tear layer atthe back surface to function as the optically active chamber. In thiscase, the front or back surface of the lens changes between refractiveshape for far vision and diffractive shape of (−1)-order diffraction fornear vision. This simplified construction allows to make the lens asthin as the corresponding segmented single focus lens.

When the wearer looks down, the lens 1450 maintains its position but thepressure from the lower lid transfers small amount of optical fluid tothe Optically Transparent Chamber of the Accommodating Cell 1500 of thelens switching it from far to near vision. As the wearer looks up, thepressure on the chamber 1480 is released and the Accommodating Cell 1500takes the relaxed state for far vision. The benefit over the segmentedlens is that there is no need to precise lens fitting for proper ridingup and down as the most of lens area is switched between far and nearvision thus simplifying the fitting and reducing a likelihood that awrong segment interferes with the vision.

Although there has been hereinabove described a specific switchablediffractive accommodating lens and method in accordance with the presentinvention for the purpose of illustrating the manner in which theinvention may be used to advantage, it should be appreciated that theinvention is not limited thereto. That is, the present invention maysuitably comprise, consist of, or consist essentially of the recitedelements. Further, the invention illustratively disclosed hereinsuitably may be practiced in the absence of any element which is notspecifically disclosed herein. Accordingly, any and all modifications,variations or equivalent arrangements which may occur to those skilledin the art, should be considered to be within the scope of the presentinvention as defined in the appended claims.

What is claimed is:
 1. An implantable ophthalmic device, comprising: adual-chamber sensor cell; a connecting element having a first endconnected to the dual-chamber sensor cell; and an accommodating lensconnected to a second end of the connecting element; wherein thedual-chamber sensor cell comprises: a first plate comprising a firsthard shell; a second plate comprising a second hard shell, the secondplate disposed opposite the first plate; a first chamber disposed on aninner side of the first plate, the first chamber comprising a firstflexible membrane; a second chamber disposed on an inner side of thesecond plate, the second chamber comprising a second flexible membrane;wherein a space resides between the first and second chambers configuredto receive a ciliary tendon or muscle fiber of a patient; wherein theconnecting element comprises: a first channel disposed along a length ofthe connecting element and in fluidic communication with the firstchamber of the dual-chamber sensor cell; a second channel disposed alongthe length of the connecting element and in fluidic communication withthe second chamber of the dual-chamber sensor cell; wherein theaccommodating lens comprises: a flexible element comprising a continuoussurface on a first side and a plurality of diffractive groove formingchannels on a second side opposite the first side, the plurality ofdiffractive groove forming channels configured to change a diffractivegroove height of the continuous surface when subjected to a pressuredifferential between the first side and second side of the flexibleelement; a first optical fluid adjacent to the continuous surface on thefirst side of the flexible element comprising a non-matching refractiveindex in relation to the flexible element; and a second optical fluidadjacent to and within the plurality of diffractive groove formingchannels on the second side of the flexible element comprising amatching refractive index in relation to the flexible element; whereinthe first channel of the connecting element is in fluidic communicationwith the first side of the flexible element; and wherein the secondchannel of the connecting element is in fluidic communication with thesecond side of the flexible element.
 2. An implantable ophthalmic deviceconnectable to an implantable accommodating lens, comprising: adual-chamber sensor cell, comprising: a first plate comprising a firsthard shell; a second plate comprising a second hard shell, the secondplate disposed opposite the first plate; a first chamber disposed on aninner side of the first plate, the first chamber comprising a firstflexible membrane; a second chamber disposed on an inner side of thesecond plate, the second chamber comprising a second soft and flexiblemembrane; wherein a space resides between the first and second chambersconfigured to receive a scleral spur of a ciliary muscle of a patient'seye; and a connecting element attached at a first end to thedual-chamber sensor cell, the connecting element comprising: a firstchannel disposed along a length of the connecting element and incommunication with the first chamber of the dual-chamber sensor cell; asecond channel disposed along the length of the connecting element andin communication with the second chamber of the dual-chamber sensorcell; wherein the second end of the connecting element is connectable tothe implantable accommodating lens.
 3. The device of claim 2, whereinthe communication of the first channel with the first chamber comprisesfluidic communication, and where the communication of the second channelwith the second chamber comprises fluidic communication.
 4. The deviceof claim 3, wherein the implantable accommodating lens comprises anaccommodating element having a formable surface on one side and aplurality of diffractive groove forming channels disposed on the otherside of said formable surface and in an operative relationship therewithfor temporarily establishing the formable surface with a non-zero reliefstructure having a variable height in response to a change of pressuredifferential applied to the formable surface on the one side and theplurality of diffractive groove forming channels on the other side. 5.The device of claim 4, including an optic combined with saidaccommodating element, said optic being selected from a group consistingof an intraocular lens or a corneal implant.
 6. The device of claim 4,wherein the first channel is connectable in fluidic communication to theone side of the accommodating element and the second channel isconnectable in fluidic communication to the other side of theaccommodating element.
 7. An implantable ophthalmic device, comprising:a sensor cell comprising a plate with a hard shell, a chamber disposedon an inner side of the plate where the chamber comprises a flexiblemembrane and wherein the flexible membrane is configured to beimplantable adjacent to a scleral spur of a ciliary muscle fiber in apatient's eye in order to change pressure in the chamber; and aconnecting element attached at a first end to the sensor cell forcommunication with the chamber of the sensor cell; and wherein thesecond end of the connecting element is connectable to an accommodatinglens.
 8. The device of claim 7, wherein the connecting element comprisesa channel disposed along a length of the connecting element where thechannel is in fluidic communication with the chamber of the sensor cell.9. The device of claim 8, wherein the accommodating lens comprises anaccommodating element having a formable surface on one side and aplurality of diffractive groove forming channels disposed on the otherside of said formable surface and in an operative relationship therewithfor temporarily establishing the formable surface with a non-zero reliefstructure having a variable height in response to a change of pressuredifferential applied to the formable surface on the one side and theplurality of diffractive groove forming channels on the other side. 10.The device of claim 9, including an optic combined with saidaccommodating element, said optic being selected from a group consistingof an intraocular lens or a corneal implant.
 11. The device of claim 9,wherein the first channel is connectable in fluidic communication to theone side or the other side of the accommodating element.
 12. Animplantable device, comprising: a sensor cell comprising a hard plateand a flexible membrane chamber disposed on an inner side of the hardplate where flexible membrane chamber is configured to be implantableadjacent to a scleral spur of a ciliary muscle fiber in a patient's eyein order to change pressure in the flexible membrane chamber due to theciliary muscle fiber's constriction and relaxation; and an implantableophthalmic lens connected to and in communication with the flexiblemembrane chamber.
 13. The device of claim 12, wherein the implantableophthalmic lens is in fluidic communication with the flexible membranechamber.
 14. The device of claim 12, including a connecting elementattached at a first end to the sensor cell, the connecting elementcomprising a channel disposed along a length of the connecting elementwhere the channel is in fluidic communication with the flexible membranechamber of the sensor cell, wherein a second end of the connectingelement is connectable to the implanted ophthalmic lens.
 15. A method oftreating presbyopia, providing at least one chamber that includes softmembrane that is implantable to be adjacent to a scleral spur of aciliary muscle of a patient's eye where the shape of the chamber changeswith the ciliary muscle contraction or relaxation and where the chamberdetects a pressure change from the ciliary muscles to communicate theciliary muscle state to an ophthalmic lens implantable in the patient'seye for a lens optical power change.